1. Field of the Invention
This invention relates to a mortise lock. More specifically, this invention relates to a mortise lock having means preventing the throwing of the deadbolt until a guardbolt is first deppessed.
2. Description of the Related Art Including Information Disclosed Under .sctn..sctn.1.97-1.99
The prior art is, of course, replete with examples of mortise locks generally comprising a rectangular housing adapted to fit into an opening in the end of the door at waist level, and generally containing a latch and a separate deadbolt and operating means for both of them. The operating means for the latch is generally in the form of a rotatable cam which is driven by a handle. For the deadbolt the operating means is usually a turnbolt on the inside of the door and a key cylinder from the outside of the door.
It has been common to use such mortise locks in the doors of guest rooms in hotels and the like with the latch bolt automatically locking when the door is closed so that the door may be opened from the hallway, only by a key operating the lock cylinder. Mortise locks to such guest rooms have also included a deadbolt operated by a turnbolt from inside the guest room.
A problem has been experienced in the past in that the guest room maid in a hotel in making up the room has abused the deadbolt. As is conventional, the linen supply for the guest rooms is brought to the hallway outside a room on a wheeled supply cart, and it is from such a cart that the maid services the room. In servicing the room the maid will strip the beds of their soiled sheets and carry them out through the door. Although the maid has a key for the room, in order to avoid having to use the key to gain readmittance to the guest room, the maid will before leaving the room simply throw the deadbolt by turning the turnbolt and then let the door swing closed on her way out. Because the deadbolt is extended, it will engage the door frame, keeping the door from closing and therefore unlatched. Later, loaded with fresh linens, the maid will merely push the door open to get back into the room.
The above-described way of operating, while saving the maid energy and time, has been hard on both the deadbolt and the door frame, because hotel doors, generally being heavy, have relatively heavy-duty closers which will drive the door toward closed position, causing a severe impact of the deadbolt on the frame.
In the past, when because of the damage caused the maid is confronted and criticized for throwing the deadbolt, she has often proclaimed her innocence, saying that it was accidental. As a result, attempts have been made in the past to make it more difficult to throw the deadbolt with the door open. An example of such an attempt is found in the U.S. Pat. Re. No. 26,677 (copy enclosed) from a patent which issued on Aug. 22, 1967 to F. J. Russel et al. In this mortise-type lock an auxiliary bolt is provided having an inward horizontal arm which carries on it a blocking element which, unless the auxiliary latch is depressed, blocks the downward movement of a special linkage pivoted to the crank arm of the deadbolt operator. The mechanism of the resissue patent has been improved upon by providing a simpler and more easily operatable structure.